SLAC’s internationally recognized theory program pursues excellence across a broad spectrum of theoretical research in advancing the frontiers of particle physics, particle astrophysics and cosmology. Theories developed by SLAC physicists help describe the nature of elementary particles and point to new symmetries of nature. They describe exciting results that could come from experiments around the world, from measurements in cosmology to particle collisions at the Large Hadron Collider. They advance models of string theory and offer important insight into our understanding of dark matter. And much, much more.